1. Field of the Invention
The present invention relates to a wiper pivot and a vehicle wiper device having the same.
2. Description of Related Art
A wiper pivot of a vehicle wiper device is arranged in such a manner that a pivot shaft rotatably supported by a pivot holder projects outwardly through a corresponding pivot hole formed through a plate (e.g., a cowl top panel) of a vehicle.
In such a wiper pivot, at the time of car wash or of rain, water enters through the pivot hole. When the water falls onto a wiper motor or a connection (e.g., a ball joint) of a link mechanism that drives the pivot shaft of the wiper pivot, it may cause an electrical trouble of the wiper motor or grease shortage of the connection of the link mechanism. Thus, in order to prevent such a trouble induced by the water applied through the pivot hole, a rubber pivot cap (also referred to as a water shield cap) is provided to the pivot holder.
The rubber pivot cap includes a tubular portion, an annular water receiver, a drain hole formed in the water receiver and a tubular drain pipe that extends axially downward from the drain hole. The tubular portion includes a plurality of annular projections in its inner peripheral surface. The pivot holder is press fitted into the tubular portion. At this time, the annular projections are tightly engaged with an outer peripheral surface of the pivot holder due to resilient force of the rubber, so that the tubular portion is secured to the pivot holder. The water receiver acts like an umbrella and extends radially outward from one end (i.e., a pivot hole side end) of the tubular portion. A size of the water receiver is larger than that of the pivot hole. Furthermore, the water receiver covers an opening side end surface of the pivot holder. The drain hole extends through the water receiver. The drain hole is formed on one side of the water receiver, which is opposite from the connection of the link mechanism. The tubular drain pipe extends axially downward from the drain hole of the water receiver. The drain pipe is arranged between ribs, which extend from the pivot holder.
In the above pivot cap, water entered through the pivot hole is received by the water receiver and is drained from the drain hole of the water receiver to the lower side of the pivot cap through the drain pipe. That is, intrusion of water between the pivot holder and the pivot cap and application of water to the connection of the link mechanism are restrained. Furthermore, the provision of the drain pipe between the ribs of the pivot holder limits rotation of the pivot cap relative to the pivot holder.
However, since the pivot cap is made of the rubber material, manufacturing costs of the rubber pivot cap are relatively high in comparison to a resin pivot cap. Furthermore, because of the rubber material, a wall thickness of the water receiver needs to be increased to maintain the shape of the water receiver, resulting in a further increase in the manufacturing costs.
To address the above disadvantages, it is conceivable to manufacture the pivot cap from a resin material. In the above case, the rubber pivot cap can be tightly secured to the pivot holder by the surface pressure of the tubular portion. However, resiliency of the resin material is smaller than that of the rubber material. Thus, when the pivot cap is made of the resin material, the securing force for securing the resin pivot cap and the pivot holder together is disadvantageously reduced. For example, such a resin pivot cap may be installed to a module type wiper device, in which components, such as a wiper motor and a link mechanism, are preassembled to serve as a module. When this module type wiper device is transported, the resin pivot cap can be relatively easily displaced from its predetermined securing position upon application of vibrations or shocks induced during the transportation. This causes improper assembly of the module type wiper device.